| AB | Automatic Behavior |
| Abdominal Movement | In diagnostic sleep studies abdominal movement is recorded. This is one of the measures of respiratory effort reflecting movement of the diaphragm. |
| ACROMEGALY | A curious condition of increased growth hormone production in adults that can present as an obstructive sleep apnoea. |
| AD | Alzheimer's Disease |
| ADA | Americans with Disabilities Act |
| Adam's Circuit | Alternative to the nose mask. Consists of nose plugs that fit at the entrance to the nose. Less stable than a mask - may be more comfortable.
|
| ADD | Attention Deficit Disorder |
| ADHD | Attention Deficit Hyperactivity Disorder |
| Advanced Sleep Phase Syndrome (ASPS) | Phases of the daily sleep/wake cycle are advanced with respect to clock time. This is classified as a circadian rhythm disorder. The sleep phase occurs well ahead of the conventional bedtime and the tendency is to wake up too early. |
| AERMS | Ambulatory electrocardiogram-respiration monitoring system |
| AHI | Apnea/Hypopnea Index |
| AHI | Apnea-Hypopnea Index. A measurement of the overall severity of sleep apnea. AHI is an average of the combined episodes of apnea and hypopnea that occur per hour of sleep. An AHI of 15 or more indicates that you have OSA. If you have symptoms of OSA such as excessive daytime sleepiness or high blood pressure then a lower AHI of 5 or more confirms that you have OSA. |
| AI | Apnea Index |
| ALCOHOL | A useful adjunct to relaxation but unfortunately it also relaxes the throat muscles and provokes snoring and obstructive apnoea. |
| Alpha intrusion | Brief occurrence of alpha activity during a stage of sleep. |
| Alpha rhythm | EEG oscillations prominent over the occipital cortex with a frequency of 8-13 Hz in adults; indicative of the awake state; present in most but not all normal individuals; most consistent and predominant during relaxed wakefulness. |
| Ambulatory Monitor | Portable system used to record (continuously) multiple physiological variables during sleep. |
| ANAESTHESIA | A dangerous time for people with sleep apnoea. The anaesthetic drugs pre-medication sedatives and post operative pain relief drugs can all worsen sleep apnoea. |
| APAP | Autotitrating Positive-Airway Pressure. These PAP units have an automatic self-adjusting mode that raises or lowers the air pressure as needed. |
| APAP (Auto-CPAP) | Auto-titrating self-adjusting device |
| Apnea | Literally means "no breath" the cessation of airflow at the nostrils and mouth for at least 10 seconds. |
| Apnea | A pause in breathing during sleep that lasts at least 10 seconds. It involves a reduction in airflow of 90% or more. This is measured by thermal sensors. |
| Apnea index (AI) | A measure of the severity of sleep apnea; the number of apnea events per hour. |
| Apnea/Hypopnea index (AHI) | The number of apneas and hypopneas per hour. 5-20=mild 21-50=moderate above 51 severe |
| APNOEA (ap-nee-ah) | A pause in breathing; conventionally more than 10 seconds. From the Greek a (without) ponea (breath). |
| Arousal | Abrupt change from sleep to wakefulness or from a "deeper" stage of non-REM sleep to a "lighter" stage |
| Arousal Disorder | parasomnia disorder presumed to be due to an abnormal arousal function. Classical arousal disorders: sleepwalking sleep terrors and confusional arousals. |
| Arousal Threshold | Ease that a sleeping person is awakened. |
| Arrhythmia | Irregularity or absence of the heart rhythm caused by disturbances in transmission of electrical impulses through cardiac tissue. |
| Auto Adjusting Continuous Positive Airway Pressure Device (SmartPAP) (Auto-PAP) | A type of CPAP machine monitoring changes in breathing and compensates automatically by making appropriate adjustments in pressure. |
| AUTO CPAP MACHINE | A clever computerised CPAP machine that adjusts its pressure automatically. Used in sleep labs but probably no better than fixed pressure machines for home use. |
| Automatism | Automatic action - especially any action performed apparently without intention or awareness. |
